Dry-Crafted Charge-Conductive ZrO_{2 - x} Cathode Shell Coating for High-Performance Sulfide-Based Solid-State Batteries

Although all-solid-state batteries (ASSBs) offer both high energy density and improved safety, the interfacial instability between sulfide-based solid electrolytes and Ni-rich layered oxide cathodes results in poor cycling stability. In this study, a charge-conductive, black ZrO_2-x (BZO_x) shell coating layer was uniformly applied to single-crystalline LiNi_0.8Mn_0.1Co_0.1O₂ (NMC) cathodes using a solvent-free and dry-processed mechanofusion method to mitigate the interfacial side reactions of sulfide-based ASSBs. The BZO_x shell coating layer effectively suppressed unwanted electrolyte decomposition and interfacial degradation while minimizing charge-transfer resistance. Moreover, BZO_x enhanced both Li ion and electron transport while contributing to interfacial stabilization with the solid electrolyte. Compared to pristine NMC and NMC coated with stoichiometric white ZrO₂, BZO_x-coated NMC exhibited improved cycling stability with higher coulombic efficiency and reduced voltage hysteresis. Our dry-crafted cathode coating strategy using charge-conductive and durable ZrO_2-x materials provides an effective pathway for enhancing the long-term operation stability of ASSBs.